The subject invention relates to a catheter and introducer needle assembly that includes a needle shield that will safely shield the sharp distal tip of the introducer needle after the needle has been used to insert the catheter into a patient. In addition, this invention includes a mechanism to connect the needle shield to the catheter until the sharp distal tip of the introducer needle is covered by the needle shield.
Catheters, particularly intravascular (IV) catheters, are used for infusing fluid, such as normal saline solution, various medicaments and total parenteral nutrition, into a patient, withdrawing blood from a patient or monitoring various parameters of the patient""s vascular system. Peripheral IV catheters tend to be relatively short, and typically are on the order of about two inches or less in length. The most common type of IV catheter is an over-the-needle peripheral IV catheter. As its name implies, an over-the-needle catheter is mounted over an introducer needle having a sharp distal tip. At least the distal portion of the catheter tightly engages the outer surface of the needle to prevent peelback of the catheter and thus facilitates insertion of the catheter into the blood vessel. The catheter and the introducer needle are assembled so that the distal tip of the introducer needle extends beyond the distal tip of the catheter with the bevel of the needle facing up away from the patient""s skin.
The catheter and introducer needle assembly is inserted at a shallow angle through the patient""s skin into a blood vessel. There are many techniques for inserting such a catheter and introducer needle assembly into a patient. In one insertion technique, the introducer needle and catheter are inserted completely into the blood vessel together. In another technique, the introducer needle is partially withdrawn into the catheter after the initial insertion into the blood vessel. The catheter is then threaded over the needle and inserted completely into the blood vessel.
In order to verify proper placement of the catheter in the blood vessel, the clinician confirms that there is flashback of blood in a flashback chamber. The flashback chamber is typically formed as part of the needle hub. Once proper placement of the catheter into the blood vessel is confirmed, the clinician applies pressure to the blood vessel by pressing down on the patient""s skin over the blood vessel distal of the introducer needle and the catheter. This finger pressure occludes or at least minimizes further blood flow through the introducer needle and the catheter. The clinician then withdraws the introducer needle, leaving the catheter in place, and attaches an appropriate device to the catheter. Such a device can include a fluid delivery device, a PRN, a deadender cap or a blood pressure monitoring probe. Once the introducer needle is withdrawn from the catheter, the introducer needle is a xe2x80x9cblood contaminated sharpxe2x80x9d and must be properly handled.
In recent years, there has been great concern over the contamination of clinicians with a patient""s blood and a recognition that xe2x80x9cblood contaminated sharpsxe2x80x9d must be disposed to avoid an accidental needle stick. This concern has arisen because of the advent of currently incurable and fatal diseases, such as Acquired Immunosuppressive Deficiency Syndrome (xe2x80x9cAIDSxe2x80x9d), which can be transmitted by the exchange of body fluids from an infected person to another person. Thus, contact with the body fluid of an AIDS infected person must be avoided. As noted above, if an introducer needle has been used to place a catheter in a blood vessel of an AIDS infected person, the introducer needle, via its sharp distal tip, is a vehicle for the transmission of the disease. Although clinicians are aware of the need to properly handle xe2x80x9cblood contaminated sharpsxe2x80x9d, unfortunately in certain medical environments, such as emergency situations or as a result of inattention or neglect, needlesticks with a contaminated introducer needle still occur.
As a result of the problem of accidental needlesticks by xe2x80x9cblood contaminated sharpsxe2x80x9d, various needle shields have been developed. Generally, such needle shields work for their intended purpose but could be improved. For example, some needle shields are bulky, difficult to use, require special features or techniques to be operative, or may leave the sharp distal tip exposed after use until the clinician manually activates the needle shielding mechanism.
In addition, some of these needle shields can be easily disconnected from the catheter hub before the needle shield covers the sharp distal tip of the introducer needle. A mechanism to avoid this premature disconnection is a plurality of fingers longitudinally extending from the needle shield with tabs extending radially inwardly from the fingers that engage the flange at the proximal end of the catheter hub. The fingers and tabs hold the needle shield to the catheter. The configuration of the fingers and tabs is designed such that the force needed to overcome the engagement between the fingers and tabs and the catheter hub is greater than the typical force needed to move the introducer needle proximally into the needle shield. However, once the introducer needle has been fully withdrawn into the needle shield, the clinician can exert a greater proximally directed force to remove the needle shield from the catheter hub. Thus the needle shield remains engaged with the catheter until the introducer needle has been completely removed from the catheter and is safely shielded in the needle shield. Unfortunately, this configuration does not consistently ensure that the needle shield remains connected to the catheter hub until the introducer needle is locked in the needle shield. This may be undesirable because the contaminated needle could then be exposed increasing the chances for an accidental needlestick.
It is therefore an object of this invention to provide a needle shield that is compact.
It is another object of this invention to provide a needle shield that is simple and easy to use.
It is still another object of this invention to provide a needle shield that requires no special features or techniques to be operative.
It is yet another object of this invention to provide a needle shield that automatically shields the sharp distal tip of the introducer needle upon withdrawal of the introducer needle from the catheter.
It is a further object of this invention to provide a catheter and introducer needle assembly with a needle shield where the needle shield remains connected to the catheter until the needle shield covers the sharp distal tip of the introducer needle.
The catheter and introducer needle assembly with needle shield of this invention includes a catheter, an introducer needle and a needle shield.
The catheter has a distal end and a proximal end connected to the distal end of a catheter hub. The catheter is coaxially disposed over the introducer needle and the distal portion of the catheter tightly engages the outer surface of the introducer needle to prevent peelback of the catheter and thus facilitate insertion of the catheter into the patient""s blood vessel. Prior to use, the catheter is located about the introducer needle so that the sharp distal tip of the introducer needle is distal of the distal end of the catheter.
The introducer needle has a sharp distal tip and a proximal end connected to the distal end of a needle hub. A flashback chamber may be defined in the needle hub. Typically a vented plug is located in the open proximal end of the flashback chamber to allow air to escape from the flashback chamber when blood enters the flashback chamber from the introducer needle. The introducer needle may also define, along a distal portion thereof, a discontinuous portion, which can take a number of different forms. For example, a slot, or an enlarged diameter portion formed on the introducer needle may be used. If an enlarged diameter portion is used it may have a tapered proximal portion or a tapered distal portion or both. The taper can be oriented at almost any angle to the longitudinal axis of the introducer needle. In certain embodiments, the distal portion may be oriented generally perpendicular to the longitudinal axis of the introducer needle. However, the main requirement is that the discontinuous portion has any configuration that cooperates with a lock associated with the needle shield to prevent unwanted distal movement of the introducer needle with respect to the needle shield. In other words, the sharp distal tip will not be re-exposed from the distal end of the needle shield once the sharp distal tip has been withdrawn into the needle shield after use. The discontinuous portion may also cooperate with a means for preventing unwanted proximal movement of the introducer needle with respect to the needle shield once the sharp distal tip of the introducer needle has been proximally withdrawn into the needle shield. This prevents re-exposure of the sharp distal tip of the introducer needle from the proximal end of the needle shield.
The needle shield is defined by a housing having an internal cavity through which the introducer needle extends. A lock associated with the needle shield prevents unwanted distal movement of the introducer needle once the introducer needle has been proximally withdrawn into the needle shield. Also associated with the needle shield is a means for preventing unwanted proximal movement of the introducer needle once the sharp distal tip of the introducer needle has been proximally withdrawn into the needle shield.
Various locks can be used to prevent unwanted distal movement of the sharp distal tip of the introducer needle out of the needle shield once the sharp distal tip has been proximally withdrawn into the introducer needle shield. For example, a transverse barrier that rides along the needle shaft as the introducer needle is withdrawn into the needle shield and that moves in front of the sharp distal tip once the needle tip is proximal of the transverse barrier may be used. In such an embodiment, no discontinuous portion is needed on the introducer needle. Alternatively, a lock may be used in conjunction with a discontinuous portion formed on the introducer needle. In such an embodiment, the lock allows the discontinuous portion of the introducer needle to move past the lock in a proximal direction but prevents movement of the discontinuous portion past the lock in a distal direction. Such a lock can take many forms and can include a spring gate, a leaf spring with one or a plurality of locking legs, where the locking legs have a variety of configurations, a tube having one or more inwardly and proximally directed tabs, a speed nut with one or more radially inwardly and proximally directed tabs extending from the main body or a retention plate with one or more radially inwardly directed tabs formed around the main body.
The spring gate has a generally U shaped configuration with a pair of spaced apart tines. The introducer needle is disposed between the tines and is moveable longitudinally past the tines. A biasing mechanism forces the spring gate up into contact with the introducer needle. With this embodiment, the discontinuous portion on the needle is preferably an enlarged diameter portion. A tapered portion immediately proximal of the enlarged diameter portion on the introducer needle may be used to facilitate proximal movement of the enlarged diameter portion past the spring gate. The enlarged diameter portion could be formed with a distally facing shoulder to provide a further positive engagement with the spring gate and minimize the possibility that a clinician could force the sharp distal tip of the introducer needle distally out of the needle shield during normal use and under normal conditions.
When the introducer needle is withdrawn proximally into the needle shield, the introducer needle rides past the tines of the spring gate. As the enlarged diameter portion passes by the tines, the enlarged diameter portion engages the tines. This forces the spring gate to rotate toward the proximal end of the introducer needle. The spring gate is also forced downwardly against the bias of the biasing mechanism. This movement by the spring gate allows the enlarged diameter portion of the introducer needle to move proximally past the spring gate. Once the enlarged diameter portion is proximal of the spring gate the biasing mechanism forces the spring gate upwardly and the tines of the spring gate rotate toward the distal end of the introducer needle. This movement of the spring gate ensures that the main portion of the introducer needle is located in the space between the tines of the spring gate so the tines extend up past the introducer needle. In this position, the spring gate abuts a proximal facing surface of a shoulder or wall in the housing to prevent further distal rotation of the spring gate. Thus, if a clinician tries to advance the introducer needle distally, the enlarged diameter portion would engage the tines of the spring gate. In addition, the spring gate would engage the wall or shoulder in the housing and prevent the introducer needle from being moved distally.
Another lock that may be used to prevent unwanted distal movement of the introducer needle once the sharp distal tip of the introducer needle has been proximally withdrawn into the introducer needle shield is a leaf spring. With the leaf spring, any configuration for the discontinuous portion can be used. However, preferably the discontinuous portion is an enlarged diameter portion on the introducer needle with a distally facing shoulder when the leaf spring is used.
The leaf spring has a proximal wall, a support leg and at least one locking leg. Preferably, the support leg and the locking leg are configured such that the locking leg extends generally back toward the proximal end of the support leg. In this configuration the support leg and the locking leg have a generally V-shape, with the apex of the V facing distally. Although this configuration is preferred, any other configuration that biases the locking leg toward the introducer needle could be used. For example, the locking leg could be generally perpendicular to the support leg or oriented at some other angle less than 90 degrees. Alternatively, the locking leg could be formed so it has a generally U-shaped or V-shaped configuration with a pair of spaced apart tines. With such a configuration the locking legs prevent unwanted distal movement of the introducer needle in a manner analogous to the spring gate discussed above. In addition, the portion of the locking leg that rides along the introducer needle shaft could be contoured to approximate a portion of the circumference of the introducer needle to minimize drag as the introducer needle rides past the locking leg.
The configuration of the leaf spring ensures that the locking leg is biased toward and abuts the main portion of the introducer needle. However this bias still allows the locking leg to ride over the enlarged diameter portion as the introducer needle is moved proximally into the needle shield. Once the distally facing shoulder of the enlarged diameter portion is moved proximally of the locking leg, the locking leg moves back into contact with the main portion of the introducer needle. Thereafter, if the introducer needle is moved distally, the locking leg will engage the distally facing shoulder and prevent further distal movement of the introducer needle.
The leaf spring and housing could be configured to maximize the mechanical engagement force between the locking leg and the introducer needle. For example, the cavity where the lock is located could have a tapered cross-section and the leaf spring could be disposed therein so it could move distally into the tapered cross-section.
In this embodiment of the leaf spring, the introducer needle would be proximally withdrawn into the needle shield just like in the previous embodiments until the discontinuous portion is proximal of the locking leg. Thereafter, if the introducer needle is moved distally, the locking leg engages the discontinuous portion and causes the lock to move distally into the tapered cross-section of the cavity. This causes the leaf spring to engage the introducer needle with increasing force until the tapered cross-section prevents further distal movement of the leaf spring. At this point, the locking leg forcefully engages the discontinuous portion preventing distal movement of the introducer needle.
In order to minimize drag on the introducer needle, the locking leg could be initially spaced apart from the introducer needle. In an alternate embodiment, the locking leg could be held out of engagement with the introducer needle by a finger and tab arrangement on the leaf spring and the housing. The leaf spring is movable proximally with respect to the housing by the engagement of the discontinuous portion of the introducer needle with the proximal wall of the leaf spring so the finger and tab can be moved out of engagement with one another. This allows the locking leg to move into engagement with the introducer needle by the inward bias of the locking leg. Thereafter, unwanted distal movement is prevented as discussed above.
In another embodiment of the leaf spring, the cavity has a distal portion and a proximal portion where the diameter of the distal portion is larger than the diameter of the proximal portion. The leaf spring is disposed in the cavity for proximal movement from the distal portion to the proximal portion. When the leaf spring is disposed in the distal portion, the locking leg does not engage the introducer needle. As the introducer needle is withdrawn proximally into the needle shield, the discontinuous portion of the introducer needle engages the proximal wall of the leaf spring. This engagement causes the leaf spring to move proximally with the introducer needle into the proximal portion of the cavity until the proximal wall of the leaf spring abuts the proximal wall of the housing. At this point, any further proximal movement of the leaf spring and the introducer needle is prevented.
When the leaf spring is in the proximal portion, the walls defining the cavity force the locking legs inwardly into engagement with the introducer needle. The leaf spring includes flexible, outwardly extending fingers. The inner walls of the proximal portion in the cavity define slots having a proximally facing wall for receiving the fingers. When the leaf spring is in the proximal portion so the proximal wall of the leaf spring abuts the proximal wall of the housing, the fingers are located in the slots so they are proximal of the proximally facing wall. Thus distal movement of the leaf spring is prevented by the engagement of the fingers and the proximally facing wall. As a result when the discontinuous portion of the introducer needle engages the locking leg, distal movement of the introducer needle is prevented.
Alternatively, the locking leg can be oriented so it is generally perpendicular to the support leg and can be formed with a small diameter opening formed therein. This opening is too small to allow the enlarged diameter portion on the introducer needle to pass therethrough but is large enough to allow the main portion of the introducer needle to pass through.
The leaf spring is held in a biased position by the shaft of the introducer needle. Thus, the locking leg rides along the introducer needle shaft as the introducer needle is retracted into the needle shield. Once the distal end of the introducer needle has been retracted into the needle shield and is proximal of the locking leg, the leaf spring returns to its unbiased position. As such, the locking leg can move so the small diameter opening in the locking leg will be aligned with the sharp distal tip of the introducer needle. Thus, If the introducer needle is moved distally with respect to the leaf spring, the distal end of the introducer needle travels through and past the small diameter opening formed in the locking leg. However, the introducer needle is prevented from being moved distally outside of the needle shield when the enlarged diameter portion on the introducer needle engages the small diameter opening formed in the locking leg.
Preferably, the housing includes at least one additional medial wall adjacent to the locking leg. This medial wall includes an opening therein to allow the main portion of the introducer needle to extend through the medial wall. This provides additional support for the introducer needle and ensures that the introducer needle is aligned with the small diameter opening in the locking leg when the leaf spring returns to its unbiased position.
A variation of the foregoing leaf spring includes an opening in the locking leg with a diameter slightly larger than the diameter of the enlarged diameter portion of the introducer needle. The leaf spring also includes a proximal wall defining an opening therein slightly larger than the diameter of the shaft of the introducer needle but smaller than the diameter of the enlarged diameter portion. The leaf spring is also slidably disposed in the housing of the needle shield but has an end portion of the locking leg that is substantially held in place with respect to the housing. This allows the locking leg to rotate in the housing.
Prior to use when the sharp distal tip of the introducer needle extends beyond the distal end of the needle shield, the locking leg is perpendicular to the longitudinal axis of the introducer needle. In this position, the introducer needle extends through the opening in the proximal wall and the opening in the locking leg. Since the diameter of the opening in the locking leg is slightly larger than the diameter of the enlarged diameter portion, it can be retracted through the opening in the locking leg so the enlarged diameter portion is proximal of the locking leg.
Once the enlarged diameter portion of the introducer needle engages the opening in the proximal wall, the leaf spring moves proximally with the introducer needle until the proximal wall of the leaf spring abuts the proximal wall of the housing. Because one end of the locking leg is substantially held in place with respect to the housing, this proximal movement of the leaf spring causes the proximal leg to rotate clockwise as seen in the FIGS. This changes the orientation of the opening in the locking leg so that a plane defining that opening is no longer perpendicular to the longitudinal axis of the introducer needle. Instead, the opening is angled so that the effective diameter of the opening, i.e. the perpendicular dimension of the opening, is less than the diameter of the enlarged diameter portion. In addition, in this position, a detent associated with the leaf spring prevents subsequent distal movement of the leaf spring. Thus any subsequent distal movement of the introducer needle is prevented since the enlarged diameter portion can not be moved through the opening in the locking leg.
An alternative lock that prevents distal movement of the sharp distal tip of the introducer needle out of the distal end of the needle shield once the sharp distal tip has been proximally withdrawn into the needle shield is a tube formed in the housing. Again, although most forms of the discontinuous portion could be used with this embodiment, the discontinuous portion is preferably an enlarged diameter portion with a distally facing shoulder. The tube is located inside the housing to allow the introducer needle to pass therethrough and includes at least one movable lanced protrusion or tab that extends proximally and inwardly into the tube. Preferably the lanced protrusion, or tab is biased inwardly. Because the lanced protrusion or tab is movable, the enlarged diameter portion of the introducer needle with the distally facing shoulder can move proximally past the lanced protrusion or tab. Once the introducer needle has been withdrawn proximally into the needle shield such that the lanced protrusion or tab is distal of the distally facing shoulder, unwanted distal movement of the introducer needle will be prevented when the distally facing shoulder engages the lanced protrusion or tab.
Although the enlarged diameter portion having a distally facing shoulder is the preferred embodiment for the discontinuous portion, a notch formed in the introducer needle could be used as the discontinuous portion. When the introducer needle is withdrawn proximally into the needle shield, one-of the lanced protrusions or tabs extends into the notch. Thereafter, distal movement of the introducer needle is prevented when the lanced protrusion or tab engages the proximal edge of the notch.
Yet another lock that prevents distal movement of the sharp distal tip of the introducer needle out of the distal end of the needle shield once the sharp distal tip has been proximally withdrawn into the needle shield is a speed nut that is formed in or added to the housing. The speed nut is located in the housing and defines a through hole and at least one proximally oriented and radially inwardly extending tab adjacent the through hole. The through hole should be slightly larger than the diameter of the introducer needle to allow the main portion of the introducer needle to pass therethrough. Because the tab is proximally oriented, the discontinuous portion can move proximally past the tab.
Once the introducer needle has been withdrawn proximally into the needle shield such that the tab is distal of the discontinuous portion, any distal movement of the introducer needle will be prevented when the discontinuous portion engages the tab. If an enlarged diameter portion is used for the discontinuous portion, it would be desirable to include a distally facing shoulder on the enlarged diameter portion to ensure firm engagement with the tab. Alternatively, the discontinuous portion may be a notch formed in the needle. When the introducer needle is proximally withdrawn into the needle shield the tab drops into the notch to thereby prevent any further distal movement of the needle when the tab engages the proximal edge of the notch. To avoid difficulties in aligning the tab and the notch, the speed nut could be formed with a plurality of tabs, each of which is configured to engage the notch. Alternatively, the introducer needle could be formed with a plurality of longitudinally displaced notches located around the circumference of the introducer needle.
In still another embodiment of the lock that prevents distal movement of the sharp distal tip of the introducer needle out of the distal end of the needle shield once the sharp distal tip has been proximally withdrawn into the needle shield, a retention plate is located on a proximal face of a medial wall formed in the housing. The wall defines an opening therein that has a diameter large enough to allow the introducer needle and the discontinuous portion to pass through. The retention plate defines at least one, but preferably a plurality of radially inwardly directed tabs. A cut out portion that has a radius substantially equal to or slightly larger than the radius of the main portion of the introducer needle but less than the radius of the enlarged diameter portion is defined between the tabs. In this embodiment, the discontinuous portion is preferably an enlarged diameter portion with a distally facing shoulder. As the introducer needle is withdrawn into the needle shield, the main portion of the introducer needle rides past the retention plate with little or no interference. As the introducer needle moves proximally with respect to the needle shield, the enlarged diameter portion of the introducer needle engages the retention plate and the tabs flex proximally so the enlarged diameter portion can travel proximally past the retention plate. Once the enlarged diameter portion of the needle is proximal of the retention plate, the tabs return to their unflexed position and abut the proximal face of the medial wall. Any subsequent distal movement of the introducer needle is prevented when the enlarged diameter portion engages the tabs of the retention plate since the housing wall prevents the tabs from flexing distally out of the way of the enlarged diameter portion.
The means for preventing further proximal movement of the introducer needle once the sharp distal tip of the introducer needle has been proximally withdrawn into the needle shield may take a number of forms. For example, where the discontinuous portion is an enlarged diameter portion, the housing may include a proximal opening that has a diameter sufficient to allow the main portion of the introducer needle to extend therethrough but that is too small to allow the enlarged diameter portion of the introducer needle from passing therethrough. Alternatively, regardless of the configuration of the discontinuous portion of the introducer needle or where no discontinuous portion is used on the introducer needle, a tether connected to the needle hub and the needle shield could be used.
The needle shield also preferably includes a spring clip that connects the needle shield to the catheter hub and that maintains this connection until the sharp distal tip of the introducer needle has been withdrawn into the needle shield and locked in place. This spring clip can take many forms.
In one embodiment, the needle shield includes a spring clip that has a clip arm that engages the catheter hub. The spring clip is biased to a position where the clip arm does not engage the catheter hub. The spring clip is held in a biased position where the clip arm engages the catheter hub by the introducer needle shaft. Thus, as long as the introducer needle extends distally past the spring clip, the clip arm remains engaged with the catheter hub and the catheter hub stays connected with the needle shield. Once the sharp distal tip of the introducer needle is withdrawn proximally past the spring clip, the clip arm moves out of engagement with the catheter hub. This allows the catheter hub to be separated from the needle shield. This configuration ensures that the needle shield remains engaged with the catheter until the introducer needle has been completely removed from the catheter and is safely shielded in the needle shield.
The spring clip can be used in combination with any of the locks discussed above for preventing unwanted distal movement of the introducer needle with respect to the needle shield. In addition, the spring clip can be formed integrally with or separately from any of those locks.
The specific configuration of the spring clip can take many different forms and can be oriented in the housing in many different ways. For example, the spring clip can have a generally V or. U shaped configuration. In this embodiment, the spring clip is located in the housing so it is perpendicular to the longitudinal axis of the introducer needle such that the V or U configuration is readily apparent from an end cross-sectional view of the needle shield. Thus one leg of the V is held in its biased position, adjacent to the other leg, by direct contact with the shaft of the introducer needle. In this arrangement, the spring clip includes a clip arm that extends generally parallel to the longitudinal axis of the introducer needle and engages a detent on the catheter hub that is oriented generally perpendicular to the longitudinal axis of the clip arm. When the introducer needle is withdrawn proximal of the spring clip, it returns to its unbiased position such that the clip arm moves transversely, i.e. generally perpendicularly to the longitudinal axis of the introducer needle, out of engagement with the catheter hub.
In an alternate embodiment, the spring clip is generally straight and is flexed into its biased position by the shaft of the introducer needle. In this embodiment, the clip arm has a hook configuration with one leg of the hook extending perpendicular to the longitudinal axis of the introducer needle with the hook facing distally. When the introducer needle is moved proximal of the spring clip, it returns to its unbiased position such that the clip arm moves transversely out of engagement with the catheter hub.
The spring clip can also be generally V or U shaped but oriented in the housing so it is aligned with the longitudinal axis of the introducer needle such that in a top cross-sectional view of the needle shield, the V or U configuration is apparent. In this configuration, the clip arm extends generally parallel to the longitudinal axis of the introducer needle and directly engages the catheter hub. However, a separate biasing arm extending generally perpendicular to the longitudinal axis of the introducer needle and connected to each of the legs of the V or U is required so the introducer needle can bias the spring clip into engagement with the catheter hub. Each biasing arm defines an opening therein and through which the introducer needle extends to achieve this biasing requirement. Once the introducer needle is moved proximal of the biasing arm, the legs of the spring clip can move to their unbiased position out of engagement with the catheter hub. Alternatively, the spring clip may be formed with only one leg such that the spring clip has a generally L-shaped shaped configuration.
Where the leaf spring uses a locking leg that is generally perpendicular to the introducer needle, the spring clip can be associated with the locking leg. The spring clip can be pivotally connected to the needle shield housing such that it is caused to pivoted between a clipped position and an unclipped position by the movement of the locking leg. Alternatively, the spring clip can be formed as a hook extending distally from the locking leg such that movement of the locking leg from the unshielded to the shielded position causes the hook to move from a clipped position to an unclipped position.
With the foregoing embodiments using a biasing arm, a means for minimizing drag on the introducer needle may be used. Such a means is a flap or finger extending from the opening in the biasing arm generally parallel to the longitudinal axis of the introducer needle. Alternatively, where two biasing arms are used, a pin and tether combination can be used. The pin extending through the biasing arms holds the openings in proper alignment so the introducer needle does not catch on the sides of the openings. A tether connected to the pin and the needle hub pulls the pin out of the biasing arms and allows the spring clip to return to its unbiased position.
Where two biasing arms are used, interlocking fingers may be located on the ends of the biasing arms such that, once the introducer needle is withdrawn proximal of the biasing arms, the interlocking fingers lock together to ensure that a non-defeatable transverse barrier is formed by the biasing arms.
In still another embodiment of the spring clip, the spring clip can be formed with a generally X shaped configuration. In this embodiment, the spring clip is oriented in the housing so the X shape is aligned with the longitudinal axis of the introducer needle such that in a top cross-sectional view of the needle shield, the X shape of the spring clip is apparent. In this embodiment, the introducer needle holds the distal portion of the legs of the X apart so they engage the inside of the catheter hub. Thus, once the introducer needle is withdrawn proximal of the intersection of the legs, the distal portion of the legs can move inwardly out of engagement with the catheter hub.
With all of the foregoing embodiments, the clip arm can be configured so it engages either the inside or the outside of the catheter hub. In addition, the clip arm can be configured frictionally or mechanically to engage the catheter hub. If a mechanical engagement is desired, the clip arm can have a detent thereon that engages a complementary detent formed on the catheter hub. Complementary detents can include, for example, a slot and a finger, or a post of any geometric shape. Regardless of the specific configuration used, the main requirement is to have the clip arm engage the catheter hub so it is difficult for the clinician to remove the catheter hub from the needle shield until the sharp distal tip of the introducer needle is shielded in the needle shield.